Recently, advances in wireless communication technologies have led to the popularization of mobile devices, and with this development there is a strong tendency for devices to use secondary batteries as a power source. Meanwhile, electric vehicles and hybrid vehicles are being developed to prevent environmental pollutions, and such vehicles also use secondary batteries as a power source.
Secondary batteries are being frequently used in various industrial fields as described above, and such secondary batteries have various outputs, capacities and structures according to their applications.
Generally, a secondary battery includes an electrode assembly having a cathode and an anode, which are formed by applying active material on the surface of current collectors, and a separator interposed between the cathode and the anode. The electrode assembly is generally received in a cylindrical or rectangular can or a pouch-type case made of an aluminum laminate sheet together with liquid or solid electrolyte. In addition, the electrode assembly may include a plurality of subsequently laminated unit electrodes, each having a thin-plate shape or a jelly-roll shape where a cathode, a separator and an anode in sheet shapes are rolled to increase the capacity of a secondary battery. Therefore, in the electrode assembly, the electrode intrinsically has a plate shape.
Such a conventional plate-shape electrode structure may be advantageous in that it may realize a high degree of integration when the electrode assembly is rolled or laminated, but there is a limit to the extent the structure can deform according to the demand of the industrial field. In addition, the plate-type electrode structure has various problems in that it is sensitive to the change in volume of the electrode during the charging/discharging process, the gas generated in the cell may not easily discharge to the outside, and the potential difference between the electrodes may increase.
In particular, to meet the various demands of the consumers, the kinds of devices using secondary batteries are diversifying and a great amount of emphasis is being put on the designs of devices. Despite this, there still remains a concept or scheme of sparing a separate portion or space in devices having unique designs in order to mount a secondary battery having a traditional structure and/or shape (e.g., cylindrical, rectangular or pouch shape) to such devices, and such a concept or scheme is considered to be a great obstacle when expanding the wireless technology and developing new designs. For example, in the case where a newly designed device is limited to only a narrow and long portion to mount a secondary battery, it is intrinsically impossible or impractical to mount a conventional secondary battery having plate-type electrodes. In other words, since the conventional cylindrical, coin-type and rectangular batteries have specific shapes, the batteries are limited in its use and ability to freely deform. In other words, since the conventional secondary batteries may not freely deform, it is impossible to twist or bend the secondary batteries in accordance with the size and/or shape of a battery mounting portion of a device.
In order to solve these problems, the applicant of this application has suggested ‘an electrode assembly with a new structure and a secondary battery having the same’, which was filed on Jan. 17, 2006 in the Republic of Korea and allowed as a patent with Korean Patent Registration No. 10-1804411, the entire contents of which are incorporated herein by reference.
The secondary battery disclosed in the above patent registration has an elongated shape, in other words a cable structure flexible in a length direction (hereinafter, this secondary battery will be referred to as a ‘cable-type secondary battery’). If a single cable-type secondary battery is mounted to a device, there is no special problem. However, in the case where a plurality of cable-type secondary batteries are used, for example when it is necessary to connect a plurality of cable-type secondary batteries in series and mount them to a device, a socket for connecting the two cable-type secondary batteries is required. Therefore, there is an urgent demand for the development of such a socket.